In numerous chemical reactions conducted using electricity, the products are recovered in the form of a fluent stream of mixed gas and liquid. In such electrochemical reactions where a recirculation loop is present in the system or where the product from a number of reactors is collected in a common receiver, there is a danger of current leakage between different parts of the reaction system or between individual reactors. Such current leakage between elements operating at different voltages or potentials can result in corrosion and loss of efficiency.
The problem is particularly noticeable in chlor-alkali electrolytic cells of the type using bipolar electrodes. In these cells, useful for the electrolysis of brines to produce halogen gas and alkali metal hydroxide, a number of individual electrolytic cell units are assembled in a bipolar mechanical and electrical configuration. Cell units made up of an anode and cathode separated by a partition are connected in series fashion to form an electrolyzer.
In the operation of such cells brine is fed to the anode compartment, where halogen gas is generated, while water is fed to the cathode compartment, where alkali metal hydroxide and co-product hydrogen gas are formed. In some instances the depleted brine and halogen gas are removed from the anolyte compartment through a common outlet, and the alkali metal hydroxide and hydrogen gas likewise flow out of a single outlet from the catholyte compartment. Often the brine and caustic will be further treated and recirculated to the respective compartments of the cell in a type of closed-loop operation.
Since bipolar electrolyzers of this type frequently operate at high current densities, it is important that the individual cells be electrically isolated. The possibility of current dissipation occurring through the product collection streams or the recirculating brine and caustic streams must be minimized for most efficient cell operation. Such current leakage between individual bipolar units or between the cell units and ground can result in a sizeable energy loss in a large electrolyzer, as well as causing severe electrochemical corrosion of the cell and associated piping. It is thus highly desirable to provide a device for interrupting the flow of current along a mixed stream of gas and liquid, and for electrically isolating the individual elements of electrochemical reactors.